Problem: If $x \otimes y = 6x-2y$ and $x \triangleleft y = 2x-3y$, find $(-4 \triangleleft -3) \otimes -3$.
Answer: First, find $-4 \triangleleft -3$ $ -4 \triangleleft -3 = (2)(-4)-(3)(-3)$ $ \hphantom{-4 \triangleleft -3} = 1$ Now, find $1 \otimes -3$ $ 1 \otimes -3 = (6)(1)-(2)(-3)$ $ \hphantom{1 \otimes -3} = 12$.